Role of hydrophobic amino acids in gurmarin, a sweetness-suppressing polypeptide.
The sweetness-suppressing polypeptide gurmarin isolated from Gymnema sylvestre consists of 35 amino acid residues and contains three intramolecular disulfide bonds. Nuclear magnetic resonance analysis showed that the hydrophobic side chains of Tyr-13, Tyr-14, Trp-28, and Trp-29 in gurmarin are oriented outwardly. Together with the hydrophobic side chains of Leu-9, Ile-11, and Pro-12, they form a hydrophobic cluster, and therefore these hydrophobic groups are assumed to act as the site for interaction with the receptor protein. To examine the roles of these hydrophobic amino acids, they were replaced by Gly. The resulting [Gly13,14,28,29] gurmarin and [Gly9,11,13,14,28,29]-gurmarin did not suppress the responses to sucrose, glucose, fructose, or Gly. This result strongly suggests that these hydrophobic amino acids are involved in the interaction with the receptor protein.
Ota
M
M
Central Research Laboratories, Ajinomoto Co., Inc., Kawasaki, Japan.
Shimizu
Y
Y
Tonosaki
K
K
Ariyoshi
Y
Y
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D004220:Disulfides / Q000737:chemistry; D004347:Drug Interactions; D005973:Glutamine / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D007532:Isoleucine / Q000737:chemistry; D007930:Leucine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000494:pharmacology; D011392:Proline / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013549:Sweetening Agents / Q000494:pharmacology*; D013649:Taste / Q000187:drug effects*; D014364:Tryptophan / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry
D000596:Amino Acids; D004220:Disulfides; D010940:Plant Proteins; D013549:Sweetening Agents; D007532:Isoleucine; D005973:Glutamine; C075206:Gurmarin protein, Gymnema sylvestre; D014443:Tyrosine; D014364:Tryptophan; D011392:Proline; D007930:Leucine; D005998:Glycine